Didier Merle

The spiral cords of the Muricidae (Gastropoda, Neogastropoda): importance of ontogenetic and topological correspondences for delineating structural homologies

The Muricidae includes about 2500 Cenozoic and Recent species. One characteristic of this radiation is its large sculptural diversification. Therefore, the shell features were used for the supraspecific classification, until anatomical studies suggested that they represent a morphological pitfall, because of their propensity to be homoplastic. However, an overlooked problem in this reconsideration is the accuracy of the shell descriptions, which generally lack ontogenetic data and precise homologies. This paper is focused on the definition of structural homologies through the spiral cords. An analytical approach emphasizes the necessity of three preliminary tests before plausibly defining them. Three main sequences of appearance of cords differing in their mode of insertion on the shell are recognized using the ontogenetic correspondence. This powerful test demonstrates that cords may evolve independently and ontogenetic changes represent a pitfall when attempting to homologize them by using the adult morphology. The topological correspondence allows identifying cords within the two major sequences and is completed by a conjunction test in order to compare all members of the family. The related characters are divided into a cord group and a groove group. Their analysis shows that differences in the expression of cord, cord spines or nodules may exist in spite of a same topological position. It also confirms that labral spines of a same type are not always homologous. Finally, the proposed method suggests that much progress is expected in order to fully understand the morphogenesis of sculptural changes characterizing this gastropod radiation.

La faune danienne de Vigny (Val-d’Oise, France) : importance pour l’étude de la diversificationdes mollusques au début du Tertiaire

The Danian fauna of mollusca from Vigny increases from 55 to 171 species distributed in 130 genera. Extended stratigraphic ranges are given for 22 genera. The Cenozoic character of the fauna relies on the 57 exclusively Tertiary genera as opposed to only 9 genera of Maastrichtian and Danian distribution, and by a species assemblage closely similar to that of the Belgian Middle Danian.

Palaeogene climate evolution in the Paris Basin from oxygen stable isotope (δ18O) compositions of marine molluscs

The constraint of temperature evolution in coastal environments is an important factor in deciphering the Earth’s global climatic history. In this study, we reconstruct the evolution of sea-surface palaeotemperatures from the oxygen stable isotope compositions in four marine molluscs families in the Paris Basin during the Palaeogene. The combination of several taxa living in different environments is used to limit uncertainties related to the influence of salinity variations on palaeotemperature estimations. One family of bivalves (oysters) and three families of gastropods (Volutidae, Cerithiidae and Turritellidae) were sampled in the French part of the Paris Basin, in Belgium and in the Isle of Wight (southern England). Maximum seawater temperatures were observed during the Early Eocene (c. 30°C), which correspond to the Early Eocene Climatic Optimum, and temperatures then decreased until the Lutetian (c. 20°C). A transient warming, identified as the Middle Eocene Climatic Optimum, occurred during the Bartonian, when temperatures reached 32°C. Temperatures decreased through the Eocene–Oligocene boundary, the coolest interval of the Palaeogene (c. 12°C). A final warming period occurred throughout the Early Oligocene, with temperatures reaching 24°C. The fossils analysed thus record the global climatic intervals of the Palaeogene. Supplementary materials: Localities, formations, isotopic data, salinities and temperatures evolutions for all fossils analyzed in this study are available at http://www.geolsoc.org.uk/SUP18839.

Les Ostracodes de la falunière de Grignon (Lutétien du Bassin de Paris): implications stratigraphiques

ABSTRACT The ostracod fauna from the outcroup “la falunière” of Grignon (Lutetian, Paris Basin): stratigraphical implications. The rehabilitation of the outcroup “la falunière” of Grignon (shell marl pit) allowed for the first time to take an almost complete section of the Paris Basin Middle Lutetian under its uncimented facies. It was the opportunity to undertake sedimentological and paleontological studies. This publication presents results of the ostracode study. More than 6000 valves or carapaces were collected and 87 species was distinguished. Three new species are described : Paracypris keiji n. sp., Neocytherideis labyrinthoidea n. sp. and Grinioneis pachycosta n. sp. The ostracodes vertical distribution in the faluns of Grignon is probably without stratigraphical signification. On the contrary, the Lutetian ostracodes associations are characteristic, as well in comparison with those of the Ypresian that with those of the Auversian or of the Barton beds. Specific diversification reflects that of the environmental niches and the wealth in individuals testify of the abundance of the food. Ostracodes indicate that the Lutetian sea was shallow, from some decimetres to some metres, probably, and its waters limpid, not much agitated. The summer temperature of water was equal at least to that of present Mediterranean Sea. From a paleogeographic point of view, the similarity between gallic fauna seems much more narrow than between whatever of this gallic fauna and those of the Aquitanian basin; so, the majority of English Lutetian species are known in the Paris Basin while the proportion of common species of the Paris Basin and of the North Aquitain basin is weak.

Taxonomic Implications of the Residual Colour Patterns of Ampullinid Gastropods and Their Contribution to the Discrimination from Naticids

Caze, B., Merle, D., Le Meur, M., Pacaud, J.-M., Ledon, D., and Saint Martin, J.-P. 2011. Taxonomic implications of the residual colour patterns of ampullinid gastropods and their contribution to the discrimination from naticids. Acta Palaeontologica Polonica 56 (2): 329–347. The diversity of residual colour patterns is revealed for the first time in the European fossil Ampullinidae. The colour patterns were studied under Ultraviolet (UV) light in approximately 3100 specimens belonging to 83 species, 12 genera (Ampullina, Globularia, Crommium, Amaurellina, Pachycrommium, Amauropsina, Ampullonatica, Eocernina, Ampullinopsis, Vanikoropsis, Pictavia, and Ampullospira) and three subgenera (Globularia, Deshayesia, and Cernina within the genus Globularia). Forty-six Cainozoic species revealed residual colour patterns and 29 of them, belonging to six genera (Ampullina, Globularia, Crommium, Amaurellina, Pachycrommium, Amauropsina), are described herein as examples representing the entire diversity of the encountered colour patterns. These patterns are most diverse during the Middle Eocene coincident with the period of highest taxonomic diversity of the Ampullinidae. Four basic classes, regarded as containing possible homologous colour patterns in terms of pigments incorporation modalities, are proposed. Class I, a fluorescent wide diffuse area or spiral stripes, occurs in most of the species, while the three others are more peculiar. Class II, fluorescent axial zigzagging stripes, Class III, fluorescent axial to slightly opisthocline stripes or segments, and Class IV, fluorescent patches forming axial segments by coalescence, allow an easy distinction between the genera Globularia, Pachycrommium, and three peculiar species of Ampullina. The bauplan of the colour patterns revealed in Globularia is very similar to that of the single extant species, Globularia (Cernina) fluctuata. This supports the view of previous authors who classified them in the same genus. Furthermore, at the family level, the peculiar residual patterns belonging to classes II, III, and IV have not been observed in naticid gastropods. Thus our results for the Cainozoic fossil record are consistent with the conclusions based on anatomy and feeding habits, namely that ampullinid gastropods, regarded for a long time as belonging to the family Naticidae, constitute a family apart.

Volutidae (Mollusca: Gastropoda) of the Lakhra Formation (Earliest Eocene, Sindh, Pakistan): systematics, biostratigraphy and paleobiogeography

The paleobiodiversity of the Volutidae (Mollusca: Gastropoda) of the Ranikot Group (Sindh, Pakistan) and particularly of the Lakhra Formation (SBZ 5 biozone, Earliest Eocene), is reconsidered on the basis of new material collected during recent field trips. Ten new species are described (Mitreola brohii sp. nov., Lyrischapa vredenburgi sp. nov., L. brevispira sp. nov., Athleta (Volutopupa) citharopsis sp. nov., A. (Volutocorbis) lasharii sp. nov., Volutilithes welcommei sp. nov., V. sindhiensis sp. nov., Pseudaulicina coxi sp. nov., Sindhiluta lakhraensis sp. nov. and Pakiluta solangii sp. nov.) and one species is in open nomenclature (Lyria sp.). Three new genera are described: Lyriopsis gen. nov. [Volutinae, ?Lyriini, type species: Lyriopsis cossmanni (Vredenburg, 1923)], Sindhiluta gen. nov. [Volutilithinae, type species: Sindhiluta lakhraensis n. sp.] and Pakiluta gen. nov. [?Volutodermatinae, type species: Pakiluta solangii n. sp.]. Two new combinations are proposed: Lyriopsis cossmanni (Vredenburg, 1923) comb. nov. and Athleta (Volutopupa) intercrenatus (Cossmann & Pissarro, 1909) comb. nov. Lectotypes are designated for Lyria cossmanni Vredenburg, 1923, L. feddeni Vredenburg, 1923, Volutospina noetlingi Cossmann & Pissarro, 1909, V. intercrenata Cossmann & Pissarro, 1909 and Athleta (Volutocorbis) victoriae Vredenburg, 1923. With 21 species, this volutid fauna is the most diverse recorded from the Tethys Ocean during Earliest Eocene time. The assemblage is characterized by a strong turnover marked by regional speciation and the appearance of many western Tethyan invaders. Although at the species level, the assemblage documents a strong provincialism, at the genus level, the high number of shared genera between Eastern Tethyan and Old World Tethyan realms begins a phase of long-term homogeneity of volutid assemblages from the Tethyan paleobiogeographic province.

New Eocene Coleoid (Cephalopoda) Diversity from Statolith Remains: Taxonomic Assignation, Fossil Record Analysis, and New Data for Calibrating Molecular Phylogenies

New coleoid cephalopods are described from statolith remains from the Middle Eocene (Middle Lutetian) of the Paris Basin. Fifteen fossil statoliths are identified and assigned to the Sepiidae (Sepia boletzkyi sp. nov.,? Sepia pira sp. nov.), Loliginidae (Loligo clarkei sp. nov.), and Ommastrephidae (genus indet.) families. The sediments containing these fossils indicate permanent aquatic settings in the infralittoral domain. These sediments range in age from 46 Mya to 43 Mya. Analysis of the fossil record of statoliths (from findings described here, together with a review of previously published data) indicates marked biases in our knowledge. Fossil statoliths are known from as far back as the Early Jurassic (199.3 to 190.8 Mya) but surprisingly, to the best of our knowledge, no record occurs in the Cretaceous. This is a “knowledge bias” and clearly calls for further studies. Finally, we attempt to compare findings described here with fossils previously used to constrain divergence and/or diversification ages of some coleoid subclades in molecular phylogenies. This comparison clearly indicates that the new records detailed here will challenge some estimated divergence times of coleoid cephalopod subclades.

Alcide d'Orbigny, un précurseur dans l'étude de la faune du Danien du bassin de Paris

Abstract One of the major contributions of Alcide d’Orbigny to palaeontology is his work on the Danian of the Paris Basin. The Danian material includes well-preserved external imprints of Invertebrates. By making casting of these imprints, Alcide d’Orbigny inaugurated an original technique, which enabled him to describe more than 40 species. The question of the age of the Danian localities has long been debated since that time. It was settled once and for all in the seventies by micropalaeontologists.

UV Light Reveals the Diversity of Jurassic Shell Colour Patterns: Examples from the Cordebugle Lagerstätte (Calvados, France)

Viewed under UV light the diverse and exceptionally well-preserved molluscs from the Late Jurassic Cordebugle Konservat Lagerstätte (Calvados, Normandy, France) reveal fluorescent fossil shell colour patterns predating the oldest previously known instance of such patterns by 100 Myr. Evidently, residual colour patterns are observable in Mesozoic molluscs by application of this non-destructive method, provided the shells are not decalcified or recrystallized. Among 46 species which are assigned to twelve gastropod families and eight bivalve families, no less than 25 species yielded positive results. Out of nine colour pattern morphologies that have been distinguished six occur in gastropods and three in bivalves. The presence of these variant morphologies clearly indicates a significant pre-Cenozoic diversification of colour patterns, especially in gastropods. In addition, the occurrence of two distinct types of fluorescence highlights a major difference in the chemical composition of the pigments involved in colour pattern formation in gastropods. This discovery enables us to discriminate members of higher clades, i.e. the Vetigastropoda emitting red fluorescence from the Caenogastropoda and Heterobranchia emitting whitish-beige to yellow fluorescence. Consequently, fluorescent colour patterns may help to allocate part of the numerous enigmatic Mesozoic gastropod taxa to their correct systematic position.

New Early Cenozoic ghost shrimps (Decapoda, Axiidea, Callianassidae) from Pakistan and their palaeobiogeographic implications

ABSTRACT A new set of Paleocene and Eocene decapod crustaceans is described from the Kirthar Range of Pakistan. Two new ghost shrimps (Crustacea, Decapoda, Callianassidae) are described: Neocallichirus khadroensis Hyžný & Charbonnier, n. sp. from the Paleocene (Danian, Khadro Formation) of Gawar Band, Ranikot District, and Neocallichirus lakhraensis Hyžný & Charbonnier, n. sp. from the Early Eocene (Ypresian, Lakhra Formation) of Rbod Nala, Jhirak District. Both new species exhibit chelipeds which are morphologically surprisingly close to extant Neocallichirus karumba (Poore & Griffin, 1979) from the Indo-West Pacific. A group of species sharing this same cheliped morphology is provisionally called the “karumba group” based on Neocallichirus karumba, best documented species. The “karumba group” encompasses seven fossil species: the two new Pakistani species, Neocallichirus tuberculatus (Lőrenthey in Lőrenthey & Beurlen, 1929) n. comb. from the Eocene of Hungary, Neocallichirus borensis Beschin, De Angeli, Checchi & Mietto, 2006 from the Eocene of Italy, Neocallichirus birmanicus (Noetling, 1901) n. comb. from the Miocene of Myanmar, Neocallichirus dijki (Martin, 1883) from the Miocene of Java and Philippines, and the subfossil Neocallichirus maximus (A. Milne-Edwards, 1870) from Thailand. Based upon the extant and fossil occurrences, it is difficult to reconstruct migration pattern of the “karumba group”. For now, it can be concluded, that at the genus level, a relative homogeneity of the ghost shrimps is observed between the Eastern and the Western Tethyan regions, as already suggested by Merle et al. (2014) for the assemblage of volutid gastropods from the Lakhra Formation.